Nanotechnology's bag of tricks for inventing new molecules and manipulating those available naturally could be dazzling in its potential to improve health care.

Evidence is accumulating that nanotechnology may enable better early warning systems for cancer and heart disease, cures for progressive diseases like cystic fibrosis, techniques for making implants like artificial hips more successful, and even artificial kidneys.

But there is no reliable timeline for the home-run projects, according to specialists like Dr. Peter R. Cavanagh, chairman of the department of biomedical engineering at the Cleveland Clinic Foundation, one of the nation's largest hospital and health research centers.

"We know how to make rubber, and we know where the road is going to go," Cavanagh told an international gathering of nanotechnology researchers and physicians at the Cleveland Clinic last week. "What we don't know is where the rubber is going to meet the road."

Nanotechnology has garnered headlines and billions of dollars of federal investment because of its potentially broad effects on all parts of commerce. It is already used in consumer products like transparent sunscreens and stain-resistant clothing. But its capacity for mixing and matching molecules seems especially suited for transforming medicine.